1. Field of the Invention
The invention relates generally to catheters for insertion into body cavities. More particularly, the invention is directed to a catheter with at least one inlet and two balloons for self-sustaining the catheter within a body cavity.
2. Background Information
Catheters are generally used in medicine to drain fluid from various body cavities. For purposes of describing the present invention, a urinary catheter is discussed. However, the same features may be applied to different catheters used to drain fluids from other body cavities.
Indwelling urinary catheters are used to treat certain medical conditions in which a patient cannot properly urinate. Such conditions may include urinary incontinence, urinary retention, trauma or problems caused by other medical conditions. By helping to void the bladder, indwelling urinary catheters facilitate the removal of waste products, such as ammonia, bilirubin and creatinine, and foreign substances, such as microbes and fungi, from the body. Indwelling urinary catheters may also be used after a major trauma or surgical procedure to drain the bladder or divert urine away from the bladder. For example, urine and blood may be diverted away from the bladder following prostate or bladder surgery. Indwelling urinary catheters are also used to assess kidney function by monitoring urine output.
The most commonly used indwelling urinary catheter is the Foley catheter. It comprises a flexible tube which extends from outside the body into the urinary bladder through the urethra. The Foley catheter comprises a main lumen and much smaller secondary lumen. The main lumen acts as a conduit to facilitate the removal of urine from the bladder and the smaller lumen is used to deliver a sterile liquid into a singular annular balloon located within the bladder above the opening of the urethra. The balloon is located near the tip of the Foley catheter and serves to retain the catheter inside the bladder. The tip of the Foley catheter also contains a urine inlet opening located above the balloon.
Although the Foley catheter is the most commonly used catheter, it has many inherent drawbacks which render it unsafe and undesirable. One major shortcoming of the Foley catheter is its inability to fully drain the bladder of urine. The pointed catheter tip and the urine inlet of the Foley catheter remain above the balloon thus causing urine to collect around the periphery of the balloon. As the urine is drained through the large lumen of the catheter, a residual volume of urine is unable to escape the bladder through the urine inlet and thus remains in the bladder. This residual volume of urine may cause serious problems for patients including the accumulation and proliferation of pathogenic organisms within the bladder which may render the patient susceptible to subsequent infection or harm to bladder and kidney tissue.
The Foley catheter may also directly damage the tissue of the bladder. For example, movement by the patient or catheter itself may result in the Foley catheter tip contacting, rubbing, irritating, or otherwise damaging the mucosal lining of the bladder, including causing lesions, bleeding, scarring and the like. Further, as the urine exits the bladder through the main lumen of the Foley catheter, a negative pressure differential is created between the main lumen and the bladder. This negative pressure differential creates a suction effect which pulls the mucosa of the bladder into the Foley catheter's urine inlet opening thus damaging the mucosal lining of the bladder. Such damage may include hemorrhagic pseudopolyps within the urinary bladder as reported by Milles, G., Catheter-Induced Hemorrhagic Pseudopolyps of the Urinary Bladder, Journal of the American Medical Association, 193(11) JAMA 968-69 (1965). Additionally, any damage to the bladder's mucosal lining caused by the Foley catheter tip may subsequently lend itself to infection by offending organisms introduced into the bladder during normal urine production or by the microbes and other pathogens present in the residual urine that has accumulate due to incomplete draining by the Foley catheter. This damage provides easy access for microbes and fungi around the normal protective tissue layers of the bladder. Therefore, the Foley catheter is both unsafe and undesirable.
Other prior art catheters do not solve all of these problems. For example, the catheter described in Nordqvist et al. (“Nordqvist”) (U.S. Pat. No. 4,575,371) does not allow for full drainage of the bladder. Nordqvist uses a single, expandable balloon that projects past the catheter tip, which is designed to prevent catheter-tip-induced injury to the mucosal wall. However, the Nordqvist single balloon may slip out of the bladder because the single balloon projects past the catheter tip resulting in an inverted mushroom-shaped configuration that is easier than, for example, the Foley catheter, to slip out of the bladder. Further, the Nordqvist catheter does not allow for complete draining of the bladder because, for example, there is no distal urine inlet at or below the distal side of the single balloon. In fact, Nordqvist places the urine inlet above the single balloon because Nordqvist states that locating the hole below the single balloon will not allow for continuous drainage due to the bladder wall closing around the single balloon. Further, the Nordqvist catheter would not allow for complete draining if, for example, the catheter shifted and urine flowed around the single balloon because the balloon completely surrounds the proximal end of the catheter thus acting as a stopper for any urine that may become trapped below the single balloon and there is no urine inlet below the balloon. The alternative embodiment described by Nordqvist wherein the single balloon contains two compartments does not cure this defect because it is still a single balloon that completely surrounds the proximal end of the catheter thus trapping urine below this single balloon and retaining a residual volume of urine in the bladder.
In Morton (U.S. Pat. No. 3,811,448), the urine inlet is located below a single balloon that is inflated on one side of the proximal end of the catheter. A urine inlet is located above and below this balloon on the side of the catheter tube that is opposite the balloon. However, as the bladder contracts upon voiding of the bladder, it conforms to the shape of the balloon. Thus, when the bladder contracts it disrupts the bowed shape of the Morton catheter by fully surrounding the single balloon and preventing urine from flowing into the distal inlet. This slows down the rate of voiding because there are less urine inlets. Further, as the bladder contracts, the catheter tube and tip contact the side of the bladder wall thus damaging the mucosal layer of the bladder. For example, the tube and tip of the Morton catheter may rub against the mucosal lining of the bladder and the mucosal lining may be pulled into both urine inlets due to the negative pressure differential between the bladder and the lumen of the catheter. Additionally, when the bladder contracts and surrounds the single balloon of the Morton catheter, a residual volume of urine remains above the balloon because the urine inlet located above the balloon is situated a certain distance away from the balloon. Therefore, a residual volume of urine will reside under the proximal urine inlet opening. Accordingly, the catheter described in Morton is unsafe and undesirable.
The Duette catheter (US 2011/0098683 A1) utilizes two balloons located on a catheter tube with one balloon above the other balloon and wherein each balloon fully surrounds the catheter tube. A urine inlet is located between the two balloons. However, the Duette catheter retains the same configuration as the Foley catheter within the bladder and the urine inlet is located above the retention balloon. Thus, the Duette catheter is equally ineffective at fully draining the bladder and a residual volume of urine remains in the bladder.
In addition to the above-mentioned drawbacks, the prior art devices have large surface areas. As such, these prior art devices are prone to the formation of biofilms on their surfaces. These biofilms act as breeding grounds for the proliferation microorganisms within the body cavity and thus expose the patient to an increased risk of infection.